1. Field of the Invention
The present invention relates to a method of creating and deleting a service flow for Robust Header-Compression (ROHC) and a wireless communication system supporting the same, and more particularly, to a method of creating and deleting a service flow for establishing a ROHC channel between ROHC entities and a wireless communication system supporting the same.
2. Discussion of the Related Art
For a wireless communication system, it is especially important to improve the utilization efficiency of limited resources. Thus, it becomes more difficult to utilize an IP protocol in a wireless interface. This is because that a portion of headers occupy a large part in data to be transmitted in the IP protocol, that is, a portion for payload becomes smaller. For instance, if VoIP is implemented using IPv4, a large amount of radio frequency bandwidth is wasted on transmitting the headers. Furthermore, a header size of IPv6 is increased so that the loss of bandwidth becomes more serious.
Under inferior communication circumstances, a bit error ratio (BER) of wireless interface, and round trip time of uplink and downlink are increased largely, which may cause problems in related art header compression methods.
In this reason, there has been arisen the necessity to amend the header compression method to be appropriate for various IP protocols and packet transmissions through the wireless interface. Especially, there is the increasing demand for the efficient header compression method which can be utilized even under the inferior circumstances with the high bit error ratio and long delay. Thus, “Internet Engineering Task Force” standardizes the header compression method known as “Robust Header Compression”.
One of the most important facts to develop the ROHC is that a redundancy exists among a plurality of IP headers used for the packet transmission, as well as within the packet. That is, most information within the header is not changed during the data packet transmission. In this case, the information included in the header can be easily reconstructed in a data-receiving station even though the information is not transmitted.
With reference to “IEEE 802.16-2004 October 2004, Air Interface for Fixed and Mobile Broadband Wireless Access Systems Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, August 2004”, “IEEE 802.16e-2005 March 2006, Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands”, “RFC 3095, Robust Header Compression (ROHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed, Bormann, C., July 2001”, “RFC 3759, Robust Header Compression (ROHC): Terminology and Channel Mapping Examples, L-E. Jonsson, April 2004”, and “WiMAX End-to-End Network Systems Architecture”, it is known that “WIBRO technology” and “WiMAX NWG” (WiMAX Worldwide Interoperability for Microwave Access Forum Network Working Group) are trying to provide a wireless Internet service to a mobile station through the use of header compression method such as the ROHC based on IEEE 802.16 technology standards.
However, there are unsolved problems considering structures and procedures for a ROHC function to realize ROHC function within the WiMAX network.